The Role of Adult Fiddler Crab Environmental Acoustic Cues and Chemical Cues in Stimulating Molting of Field-Caught Megalopae

In mid-Atlantic estuaries, three fiddler crab species, Uca pugilator, Uca pugnax and Uca minax co-occur, with their adults occupying different habitat types distinguished by salinity and sediment size. Some evidence exists that selective settlement is responsible for this separation but the mechanism is largely unknown. We tested the hypothesis that field-caught megalopae would accelerate metamorphosis in the presence of adult species-specific environmental acoustic cues and conspecific chemical cues. We placed megalopae in seawater with and without adult chemical cues, exposed them to one of three sound treatments for 8 days, and recorded the time each megalopa took to metamorphose. In the absence of adult chemical cues, very few megalopae molted regardless of sound treatment. Molting in the presence of habitat sound and chemical cues varied by species. Many U. pugilator molted in all sound and odor combinations, including no odor/sound. U. pugnax was stimulated to molt by chemical cues from either U. pugilator or U. pugnax, but molting was similar across sound treatments. Our results do not support the hypothesis that sound stimulates molting by fiddler crab megalopae, but support the role of chemical odors from adults as molting cues

Editorial - East and Central African Journal of Surgery: The Canadian connection

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Credits

Credits

Editor's Note

A welcome note from the Editor-in-Chief

Sickness presenteeism: measurement and management challenges

Since work can be restorative to health, attending work when unwell should not be viewed as an inherently negative phenomenon. However, the functional benefits are likely to depend on the health condition, and the psychosocial quality of the work provided. The current study used a workforce survey to explore differences in the pattern of presenteeism and absenteeism by health condition, the association of psychosocial work factors with presenteeism compared to absenteeism, and their interaction to predict health. Findings indicate that instead of substituting absenteeism for presenteeism, the two tend to coincide, but the balance differs by health condition. Presenteeism is more likely to occur in poorer psychosocial environments, reinforcing the importance of ensuring work is designed and managed in ways that are beneficial rather than detrimental to health. The findings also highlight the methodological importance of differentiating between the act and impact of presenteeism in future research and practice

The biological effects of air ions and electrostatic fields

Over a number of years while working in the climatic chambers at the R.A.F. Institute of Aviation Medicine it has often been noticed that there is a depressing and tiring effect which is difficult to explain in terms of the more usual climatic parameters of temperature and humidity. Similar symptoms in enclosed air conditioned spaces have been noticed by other people both within the Ministry of Defence and elsewhere. The lethargic feeling resembles that associated with heavy thundery weather and with certain winds of ill repute which are found in some parts of the world and whose effects are difficult to explain in terms of temperature and humidity alone. Because of the electrical disturbances taking place in the atmosphere as a prelude to storms it has been proposed, that the reported symptoms in the natural and artificial environment are in some way associated with the local electrical climate. In Part 1. of this thesis the physics of air ions and electrostatic fields, the two constituents of Man's Physical Environment which have received most attention in this context, are examined to try to understand their role in the natural environment and in situations created artificially for studying their biological effect. The results of experimental work reported in the literature are reviewed to try to delineate any physiological mechanism which might be sensitive to such a small natural stimulus. In some countries negative ion therapy is practiced for the alleviation of certain disorders, many of which are psychosomatic in nature, but there are indications that it might be beneficial in post-operative healing and the treatment of burns. Part 2. deals with two. experimental series, the first of which tests the effect of various strengths and configurations of electrostatic fields on the spontaneous activity and growth rate of rats living within the field. The second series examines the effect on the same parameter of living in an ion-free atmosphere. In both series of experiments the results were found to be negative but increase in air movement was shown to have an inhibitory effect on both spontaneous activity and growth rate. This finding adds weight to a criticism which can be levelled at much of the experimental work reported in the literature, that not sufficient attention is paid to controlling the normal climatic parameters

Editorial

Editorial by Dr. James F. Waddel

The eMerging Dependence of SMEs and Citizens on Broadband

In October 2006, the Broadband Wales Observatory undertook case study research into the change, impact and benefits of broadband, on a diverse selection of SMEs (including micro and SOHO businesses) and citizens from across Wales, UK. This paper explains the research approach and method, and presents an overview of the findings from 24 case study reports. It concludes that all of the cases have embraced ADSL broadband, increasing their use and dependency on Internet communication methods, and that many have also re-engineered their business processes to achieve improved operational efficiencies and productivity gains

Program Manager Competencies (Chapter 11 of Program Management for Improved Business Results)

The successful program manager is constantly seeking to learn and broaden his or her knowledge and experience in order to take on more complex and critical programs. The program management competency model was developed in order to address the breadth, depth, and complexity of the program management role. This chapter uses the program management competency model to detail the knowledge, skills, and abilities needed for program managers to continually grow as professionals and consistently succeed in their role. The various types of competencies that are discussed in the chapter are: customer and market competencies, business and financial competencies, process and project management competencies, and leadership competencies. Additionally, the chapter discusses the key organizational enablers needed to make the competency model fully effective and to adequately support the program management discipline within an organization